Conventionally, various types of batteries have been developed. In these batteries, a battery element consisting of electrodes, an electrolyte and so on needs to be sealed in a packaging material or the like. As such a battery packaging material, metal packaging materials are generally used.
In association with the recent advanced performance of electric cars, hybrid electric cars, personal computers, cameras, mobile phones and so on, batteries having a variety of forms are demanded. It is also requested for batteries to have smaller thickness and lighter weight. However, metal packaging materials that are generally used heretofore have difficulty in keeping up with the diversified forms of batteries. Also weight reduction is limited because the packaging materials are made of metal.
Thus, there has been proposed a film-shaped laminate with a base material layer, a metal layer and a sealant layer laminated in this order has been proposed as a battery packaging material which is easily processed into diversified shapes and is capable of achieving thickness reduction and weight reduction.
For example, Patent Document 1 discloses a packaging material for a battery casing, including a biaxially-oriented polyamide film layer as an outer layer, a thermoplastic resin non-oriented film layer as an inner layer, and an aluminum foil layer disposed between these films.